In administering a medical liquid into a patient's body through an intravenous (I.V.) dripping system, it should be very carefully to always monitor the dripping liquid level in the I.V. container or bag, easily causing fatigue to a nurse or a patient's companion. It may be inadvertently cared to empty the I.V. liquid in the administering dripping system especially when tired or sleepy at night time, thereby causing a backflow of the patient's blood into the needle or delivery tube of the dripping system having air enterring therein and the backflow blood may coagulate to clog the needle from administering I.V. liquid. The clogged needle or cannula should be replaced with a new one and an intravenous injection spot on the patient's skin or body should be repeatedly searched causing inconvenience for a nurse and also sticking injury to the patient.